This invention relates in general to battery chargers for portable electric and electronic devices, and more particularly to ensuring compatibility with chargers used to charge the battery of a portable device.
Portable electric and electronic devices are in widespread use, and there is a large market for rechargeable batteries and battery chargers. For devices that are in near constant use, it is more cost effective to use rechargeable batteries instead of primary batteries. Examples of such devices are cellular radiotelephones and laptop computers.
Recent advances in battery and electrochemical technology have yielded high capacity battery designs such as that known as lithium ion (Li-ion). Li-ion cells provided a large improvement in energy capacity per unit weight and volume over earlier technologies such as nickel cadmium and nickel hydride technologies. However, Li-ion batteries require a carefully controlled charging regimen to prevent damaging the battery cells. Improperly charging a Li-ion battery can severely shorten its cycle life, its capacity, and may even cause physical damage to the battery cell case, resulting in leakage.
Furthermore, cellular radiotelephones typically now contain charger control circuitry internally, and charging with an incompatible power supply can damage the charger circuitry, or lead to poor performance. If the power supply voltage is too high, it can damage the device. Excessive voltage can cause unanticipated power dissipation in the device, which heats and damages the battery, or can cause a fire risk.
With the great number of chargers presently on the market, there is a risk of an incompatible charger being used to charge a Li-ion battery. When a battery is damaged due to an incompatible charger, the perception is that the quality of the portable device or the battery itself is poor. Therefore there is a need for a means by which an incompatible charger can be identified, and indicated to a user of the portable device.